This invention relates to a throttle control for an outboard motor and more particularly to an improved intake air silencing arrangement for an internal combustion engine such as is employed in an outboard motor.
As is generally well known, an outboard motor provides quite a number of design challenges for the engineer. Although the overall construction of an outboard motor is relatively simple and compact, because of this compactness there is very space little available for silencing of the induction system and exhaust noises associated with such outboard motors as well as the transmission of mechanical to the atmosphere through these systems. One area that provides particular difficulty is the transmission of noise from and/or through the induction system for the engine.
The induction system for an outboard motor must be designed so as to provide adequate air flow under a wide range of running conditions, particularly extended periods at full throttle. Also, the induction system should be designed in such a way as to inhibit the ingestion of water from the atmosphere into the engine through the induction system. Finally, it is important that the induction system be designed in such a way as to not generate significant noise that can be objectionable to the operator.
Therefore, it has been generally proposed to employ some form of silencing device in the intake system that includes one or more air inlet openings that deliver air to a plenum chamber and from there to the engine through the throttle bodies. Although various types of silencing arrangements have been proposed, they generally must be designed to be particularly effective at a certain speed and load range and also should be such that they do not restrict the airflow necessary to obtain maximum performance. Therefore, the conventional induction system is designed so as to primarily provide adequate air flow for high speed running. This results in considerable noise generation and transmission under other running conditions.
Although the induction system can be tuned to provide silencing at these other conditions, the tuning will restrict the airflow to the engine and hence, adversely effect maximum power output.
It is, therefore, a principal object of this invention to provide an improved induction system for an internal combustion engine and particularly one associated with an outboard motor.
It is a further object of this invention to provide an induction system that is capable of silencing induction system sounds and mechanical sounds transmitted through the induction system over a wide range of running conditions without restricting the necessary air flow to achieve the desired engine performance.
It if a further object of this invention to provide an improved air inlet device for an outboard motor.